IELTS Writing Task 1 Process Diagrams: How to Describe Them

Process diagrams trip up more IELTS candidates than almost any other Task 1 type. Not because they are especially hard, but because most people treat them like a flowchart they need to narrate out loud rather than a structured piece of academic writing. There is a difference, and knowing it will push your score up.

This lesson focuses on one thing: how to describe a process diagram accurately, coherently, and in a way that actually sounds like written English rather than a spoken commentary.

Why Process Diagrams Are Different

In a bar chart or pie chart task, you are comparing data. Numbers go up, numbers go down, you describe the trends. Simple enough.

A process diagram has no data. It shows a sequence of stages, often with arrows connecting them. Your job is to explain how something works or how something is made, from start to finish, in clear and logical order.

That means two things matter most: sequencing language and the passive voice.

Get those two right, and you are most of the way there.

The Lesson: Structure and Language

Let’s say the diagram shows how bricks are manufactured. There are stages: clay is extracted, it is mixed with water, it is moulded, it is dried, it is fired in a kiln, and then it is packaged and delivered.

Notice something about that sentence. Almost every verb is passive. Is extracted. Is mixed. Is moulded. That is entirely intentional. In process diagrams, the focus is on what happens to the material or product, not on who does it. The passive voice is not a stylistic flourish here. It is the correct and expected choice.

Here is a weak opening that many candidates write:

The diagram shows the process of making bricks. First, workers get clay from the ground. Then they mix it with water.

And here is a stronger version:

The diagram illustrates the process by which bricks are manufactured, beginning with the extraction of clay and culminating in the delivery of the finished product. The process involves six distinct stages.

The second version does three things well. It paraphrases the task without copying it word for word. It signals the overall scope of the process. And it sets up the body paragraphs logically.

For the body, split the stages roughly in half. Describe the first half in one paragraph, the second half in another. Use sequencing language to link each stage:

• To begin / Initially — for the first stage
• Following this / Subsequently / Once this is complete — for middle stages
• Finally / At the final stage — for the end

You do not need a conclusion. A brief overview at the start (as shown above) is enough. Some candidates also add a short final sentence summarising the number of stages or the general nature of the process, and that is perfectly fine.

If you want a template to practise with and a tutor to give you line-by-line feedback on your attempts, that is exactly what we do in the daily coaching programme. For more details, click here.

The Common Mistake

The most frequent error is over-using active voice and making the writing sound like instructions rather than a description.

Compare these two sentences:

Weak: You put the clay into a mould and leave it to dry for 24 hours.

Stronger: The clay is placed into a mould, where it is left to dry for approximately 24 hours.

The weak version sounds like a recipe. The stronger version sounds like an academic description of an industrial process, which is what the examiner is looking for.

A second common mistake is forgetting that the diagram may show a cyclical process rather than a linear one. If the last stage loops back to the first (common in natural processes like the water cycle), you need to say so. Something like: This final stage returns the water to the atmosphere, completing the cycle. Missing that loop means missing a key feature of the diagram, which will cost you marks for Task Achievement.

Practice Tips You Can Use Today

1. Passive voice drill. Take any paragraph you have written recently and rewrite every active sentence in the passive. Then decide which version reads better in context. Do this for ten minutes and your instinct for when to use the passive will sharpen noticeably.
2. Sequence without looking. Find a process diagram online (there are dozens on IELTS preparation sites). Study it for two minutes, then close the image and write your description from memory. When you look back, check whether you captured every stage and whether your sequencing language made the order clear.
3. Time yourself strictly. Task 1 should take no more than 20 minutes in the real exam. Set a timer. If you are regularly going over, the problem is usually that you are writing too much. The target is around 170 to 190 words, not 250.

Vocabulary to Know

• to illustrate /ɪˈlʌstreɪt/ – Level: B1 – to show or explain something using diagrams, examples, or descriptions – Example: The diagram illustrates the stages involved in water purification.
• sequential /sɪˈkwenʃəl/ – Level: B2 – following a specific order, one stage after another – Example: The process is sequential, with each stage depending on the completion of the previous one.
• culminate in /ˈkʌlmɪneɪt ɪn/ – Level: B2 – to reach a final result or end point after a series of stages – Example: The manufacturing process culminates in the packaging of the finished goods.
• subsequently /ˈsʌbsɪkwəntli/ – Level: B2 – happening after something else, used to show the next step in a sequence – Example: The mixture is heated and subsequently filtered to remove impurities.
• cyclical process /ˈsɪklɪkəl ˈprəʊses/ – Level: B2 – a process in which the final stage leads back to the beginning, repeating continuously – Example: The water cycle is a cyclical process with no clear start or end point.
• passive construction /ˈpæsɪv kənˈstrʌkʃən/ – Level: B2 – a grammatical structure where the subject receives the action rather than performing it – Example: In IELTS process descriptions, passive constructions are generally preferred over active ones.
• extracted /ɪkˈstræktɪd/ – Level: B1 – removed or taken out from a source, often used in manufacturing or industrial contexts – Example: Raw materials are extracted from the mine before being transported to the factory.
• distinct stage /dɪˈstɪŋkt steɪdʒ/ – Level: B2 – a clearly separate and identifiable step within a process – Example: The diagram shows five distinct stages in the production of paper.
• overview /ˈəʊvəvjuː/ – Level: B1 – a general summary that captures the main features without going into detail – Example: A well-written overview identifies the nature and scope of the process before describing individual stages.
• to undergo /ˌʌndəˈɡəʊ/ – Level: C1 – to experience or be subjected to a process or change – Example: The raw material undergoes several chemical treatments before it reaches its final form.

FAQ

Do I need to describe every single stage in the diagram?

Yes. Unlike graphs where you select the most significant data, process diagrams require you to cover all stages. Missing one is a Task Achievement error. You do not need to write the same amount about each stage, but all of them should appear in your response.

Should I write an introduction, body, and conclusion like an essay?

Not quite. You need an introduction (a paraphrased overview of the process), one or two body paragraphs covering the stages in order, and that is it. A formal conclusion is not necessary and often wastes your limited word count. Keep it tight.

How formal does my language need to be?

Fairly formal. You are writing an academic description, not a casual explanation. Avoid contractions, avoid first person (do not write “I can see that…”), and stick to precise, neutral vocabulary. The passive voice helps you maintain that register naturally.

Process diagrams reward candidates who are methodical. Learn the structure, practise the passive, and cover every stage. That is the formula. If you want structured practice with feedback on real exam tasks, the daily coaching programme at richardg.xyz is built around exactly this kind of focused work. Find out more here.